U.S. Pat. No. 5,095,072 has described thermoplastic blends of PVDF and of rubber of nitrile or acrylate type in the gel form. The gelling of the rubber is obtained by addition of multifunctional monomers or by high-temperature polymerization and not by vulcanization. The gelled rubber is then mixed with the PVDF; it is found that the gelled rubber is distributed crudely and unevenly in the PVDF and that the blends obtained exhibit no tensile, flexural or impact-resistant properties, which generally characterizes heterogeneous mixtures of polymers.
EP 714,944 has provided thermoplastic compositions comprising a poly(vinylidene fluoride) (PVDF) matrix in which are dispersed nodules of essentially non-fluorinated vulcanized rubber which exhibit improved mechanical properties in comparison with the blends described in U.S. Pat. No. 5,095,072. In order to improve the multiaxial impact strength, EP 714,944 recommends the addition of a compatibilizing agent chosen from optionally grafted aliphatic polyesters, optionally imidized poly(methyl methacrylate) (PMMA) or polyolefins grafted with methyl methacrylate. These compatibilizing agents often have mediocre chemical and mechanical properties, which has a harmful influence on the compositions onto which they are introduced.